Test Codes - BSPT & BSPP Threads - RYCO Hydraulics

BSPT & BSPP Threads

  • BSP is BRITISH STANDARD PIPE – Also known as Whitworth 55° Thread Form
  • BSPT is BRITISH STANDARD PIPE TAPER – THREAD FORM PER AS 1722.1, BS 21, ISO 7-1, DIN 3852-2 FORM C (MALE), DIN 3852-2 FORM Z (FEMALE)
  • BSPP is BRITISH STANDARD PIPE PARALLEL – THREAD FORM PER AS 1722.2, ISO 228 (THREAD TYPE), ISO 1179
  • BSPO IS BRITISH STANDARD PIPE PARALLEL O-RING – THREAD FORM PER AS 1722.2, ISO 228 (THREAD TYPE), ISO 8434-6, BS 5200
BSPT & BSPP Threads

British Standard Pipe threads are similar in function to NPT threads, but are generally not interchangeable.

BSPT male threads seal against threads of fixed BSPT female.
Contact is made on the flanks of the threads.

Use of a thread sealant is recommended for BSPT male to BSPT female connections.
Measure the BSPT male thread OD and female thread ID at the first full thread near the end of the fitting.

BSPT male and BSPP male with conical 30° seat (60° included angle) seal against matching conical 30° seat of BSPP female swivel.

BSPT & BSPP Threads

BSPP O Ring male connector has straight threads and O Ring with metal Retaining Ring. It seals against flat external surface of BSPP female port.
BSPP male, with chamfer to locate Bonded Seal also seals against flat external surface of BSPP female port.

Surface irregularities require a Spot Face to ensure effective sealing. Elbows and tees have Lock Nut to allow orientation of fitting to required direction.

BSPT & BSPP Threads

BSPP male and BSPP female flat face swivel require a suitable soft washer between faces to seal. For low working pressure.

BSPT & BSPP SIZE & PITCH DASH SIZE BSPT MALE THREAD OD BSPP MALE THREAD OD BSPT FEMALE THREAD ID BSPP FEMALE THREAD ID
inch-TPI mm inch mm inch mm inch mm inch
1/8 – 28 -02 9,5 0.37 9,6 0.38 8,4 0.33 8,6 0.34
1/4 – 19 -04 12,8 0.50 13,0 0.51 11,2 0.44 11,9 0.47
3/8 – 19 -06 16,3 0.64 16,5 0.65 14,7 0.59 15,2 0.60
1/2 – 14 -08 20,4 0.80 20,8 0.82 18,3 0.72 19,1 0.75
5/8 – 14 -10 22,5 0.89 22,8 0.90 20,6 0.81 20,8 0.82
3/4 – 14 -12 25,9 1.02 26,3 1.04 23,9 0.94 24,6 0.97
1 – 11 -16 32,6 1.28 33,1 1.30 29,7 1.17 30,7 1.21
1.1/4 – 11 -20 41,1 1.62 41,8 1.64 38,6 1.52 39,4 1.55
1.1/2 – 11 -24 47,0 1.85 47,7 1.88 44,5 1.75 45,5 1.79
2 -11 -32 58,6 2.31 59,5 2.34 56,4 2.22 57,4 2.26
2.1/2 – 11 -40 74,1 2.92 75,1 2.95 71,9 2.83 72,6 2.86
3 – 11 -48 86,6 3.41 87,9 3.46 84,6 3.33 85,4 3.36

Thread size refers to the nominal bore of the pipe. Subtract approx. 1/4″ (6mm) from thread diameter measurement for nominal pipe size.
Pitch is Threads Per Inch (TPI). “Gas”, “R” & “G” also refer to BSP. “Male Iron (Pipe)” may be BSP or NPT.

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